DESCRIPTION: (Verbatim) - The goal of this proposal is to optimize the barrier function properties of a human skin equivalent culture for eventual commercialization as an in vitro test for chemicals and formulations. Human skin equivalent assays are the best alternative to animal testing for evaluating the effect of chemicals on the barrier properties of human skin. Such tests are needed to prevent the inclusion of ingredients in consumer products, cosmetics or topically applied pharmaceuticals that would damage this critical function of skin. The tests also are needed to discover new ways of safely disrupting barrier function for the transdermal delivery of new pharmaceuticals. The skin equivalent cultures currently available have much poorer barrier function properties than human skin and are therefore inadequate for testing barrier function. The proposal will utilize a new and proprietary human skin cell line called NIKS(TM) (normal immortalized keratinocytes). NIKS(TM) cells can establish fully differentiated organotypic cultures of human skin. In contrast to primary keratinocytes, the immortalized NIKS(TM) cells can be used to establish genetically altered cell lines. The present studies will use this novel property of NIKS(TM) cells, as well as optimization of the culture conditions, to generate skin equivalent cultures with improved barrier function. PROPOSED COMMERCIAL APPLICATION: The goal of these studies is to provide a commercial skin substitute for in vitro pharmacological and toxicological testing assays that has barrier function comparable to that of normal skin. Cosmetic companies spend approximately $50 million to $100 million per year on safety testing new compounds and formulations on animal or human skin. Household product and pharmaceutical companies make similar expenditures. Current skin substitutes are significantly defective in barrier function. These industries need a simple assay system that mimics the barrier properties of human skin. Stratatech is developing products and contract services for this large market using its proprietary skin cell line.